Efficient electrochemical reduction of CO to C2 products on the transition metal and boron co-doped black phosphorene

TM2 -B2 Quadruple Active Sites Supported on a Defective C3 N Monolayer as Catalyst for the Electrochemical CO2 Reduction: A Theoretical Perspective

Developing high-performance electrocatalysts for the CO₂ reduction reaction (CO₂ RR) holds great potential to mitigate the depletion of fossil feedstocks and abate the emission of CO₂ . In this contribution, using density functional theory calculations, we systematically investigated the CO₂ RR performance catalyzed by TM₂ -B₂ (TM=Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu) supported on a defective C₃ N monolayer (V-C₃ N). Through the screening in terms of stability of catalyst, activity towards CO₂ adsorption, and selectivity against hydrogen evolution reaction, Mn₂ -, Fe₂ -, Co₂ -, and Ni₂ -B₂ @V-C₃ N were demonstrated to be a highly promising CO₂ RR electrocatalyst. Due to quadruple active sites, these candidates can adsorb two or three CO₂ molecules. Strikingly, different products, distributing from C₁ to C₂₊ , can be generated. The high activity originates from the synergistic effect of TM and B atoms, in which they serve as adsorption sites for the C- and O-species, respectively. The high selectivity towards C₂₊ products at the Fe₂ -, and Ni₂ -B₂ sites stems from moderate C adsorption strength but relatively weak O adsorption strength, in which a universal descriptor, that is, 0.6 ΔE_C -0.4 ΔE_O =-1.77 eV (ΔE_C /ΔE_O is the adsorption energy of C/O), was proposed. This work would offer a novel perspective for the design of high active electrocatalysts towards CO₂ RR and for the synthesis of C₂₊ compounds.

Computational screening of single-atom catalysts supported by VS2 monolayers for electrocatalytic oxygen reduction/evolution reactions

The development of highly efficient bifunctional electrocatalysts to boost oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is highly desirable for energy conversion and storage devices. Herein, by means of comprehensive first-principles computations, we systematically explored the catalytic activities of a series of single transition metal atoms anchored on two-dimensional VS₂ monolayers (TM@VS₂) for ORR/OER. Our results revealed that Ni@VS₂ exhibits low overpotentials for both ORR (0.45 V) and OER (0.31 V), suggesting its great potential as a bifunctional catalyst, which is mainly induced by its moderate interaction with oxygenated intermediates according to the established scaling relationship and volcano plot. Interestingly, the substituted doping of nitrogen heteroatoms into the VS₂ substrate can further effectively improve the ORR/OER activity of the active metal atom to achieve more eligible ORR/OER bifunctional catalysts. Our results not only propose a new class of potential bifunctional oxygen catalysts but also offer a feasible strategy for further tuning their catalytic activity.